diff --git a/src/google/protobuf/reflection_mode.cc b/src/google/protobuf/reflection_mode.cc
new file mode 100644
index 0000000..f87d816
--- /dev/null
+++ b/src/google/protobuf/reflection_mode.cc
@@ -0,0 +1,50 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2022 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+#include "google/protobuf/reflection_mode.h"
+
+namespace google {
+namespace protobuf {
+
+namespace {
+
+thread_local ReflectionMode reflection_mode = ReflectionMode::kDefault;
+
+}  // namespace
+
+ReflectionMode GetReflectionMode() { return reflection_mode; }
+
+ReflectionMode SetReflectionMode(ReflectionMode mode) {
+  ReflectionMode previous_mode = reflection_mode;
+  reflection_mode = mode;
+  return previous_mode;
+}
+
+}  // namespace protobuf
+}  // namespace google
diff --git a/src/google/protobuf/reflection_mode.h b/src/google/protobuf/reflection_mode.h
new file mode 100644
index 0000000..04342f7
--- /dev/null
+++ b/src/google/protobuf/reflection_mode.h
@@ -0,0 +1,84 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2022 Google Inc.  All rights reserved.
+// https://developers.google.com/protocol-buffers/
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// This header provides support for a per thread 'reflection mode'.
+//
+// Some protocol buffer optimizations use interceptors to determine which
+// fields are effectively used in the application. These optimizations are
+// disabled if certain reflection calls are intercepted as the assumption is
+// then that any field data can be accessed.
+//
+// The 'reflection mode' defined in this header is intended to be used by
+// logic such as ad-hoc profilers to indicate that any scoped reflection usage
+// is not originating from, or affecting application code. This reflection mode
+// can then be used by such interceptors to ignore any reflection calls not
+// affecting the application behavior.
+
+#ifndef GOOGLE_PROTOBUF_REFLECTION_MODE_H__
+#define GOOGLE_PROTOBUF_REFLECTION_MODE_H__
+
+namespace google {
+namespace protobuf {
+
+// Reflection modes.
+enum class ReflectionMode {
+  kDefault,      // Default mode
+  kDiagnostics,  // Reflection is invoked as part of some external diagnostics
+};
+
+// Returns the current reflection mode
+ReflectionMode GetReflectionMode();
+
+// Sets the current reflection mode. Returns the previous reflection mode.
+// Application code should prefer to use the `ScopedReflectionMode` class.
+ReflectionMode SetReflectionMode(ReflectionMode mode);
+
+// Scoping class to set the specific reflection mode for a given scope.
+class ScopedReflectionMode {
+ public:
+  // Sets the current reflection mode, which will be restored at destruction.
+  explicit ScopedReflectionMode(ReflectionMode mode)
+      : previous_mode_(SetReflectionMode(mode)) {}
+
+  // Restores the previous reflection mode.
+  ~ScopedReflectionMode() { SetReflectionMode(previous_mode_); }
+
+  // ScopedReflectionMode is neither copyable, movable nor assignable.
+  ScopedReflectionMode(const ScopedReflectionMode&) = delete;
+  ScopedReflectionMode& operator=(const ScopedReflectionMode&) = delete;
+
+ private:
+  const ReflectionMode previous_mode_;
+};
+
+}  // namespace protobuf
+}  // namespace google
+
+#endif  // GOOGLE_PROTOBUF_REFLECTION_MODE_H__
diff --git a/src/google/protobuf/text_format.cc b/src/google/protobuf/text_format.cc
index d6298c8..956dab7 100644
--- a/src/google/protobuf/text_format.cc
+++ b/src/google/protobuf/text_format.cc
@@ -64,6 +64,7 @@
 #include "google/protobuf/io/zero_copy_stream_impl.h"
 #include "google/protobuf/map_field.h"
 #include "google/protobuf/message.h"
+#include "google/protobuf/reflection_mode.h"
 #include "google/protobuf/repeated_field.h"
 #include "google/protobuf/unknown_field_set.h"
 #include "google/protobuf/wire_format_lite.h"
@@ -103,6 +104,10 @@
 }  // namespace internal
 
 std::string Message::DebugString() const {
+  // `TextFormat::Printer` is implemented in terms of reflection: indicate
+  // that any scoped reflection calls are for diagnostics purposes only.
+  ScopedReflectionMode scoped(ReflectionMode::kDiagnostics);
+
   std::string debug_string;
 
   TextFormat::Printer printer;